In a pot of boiling water, add the thyme and diced parsnip and celery root. Cook for several minutes until tender. Remove the parsnip and celery root from the water and set aside. In the same pot, add the diced carrot and blanch until tender. Strain and add to the parsnip and celery root. Set aside to cool.

For the vinaigrette, combine the parsley, tarragon, chervil and chives with the crème fraiche and red wine vinegar. Add salt and pepper to taste. Toss dressing with root vegetable mixture.